'4 engines 4 long haul' was a phrase that famously adorned the fuselages and engines of Virgin Atlantic's Airbus A340 and Boeing 747 fleet. For a long time many have believed this true, but are things about to change?

ETOPS, or Extended Range Twin Operations, is a certification a twin engined aircraft requires to fly over extended bodies of water or sparsely populated terrain such as mountains or large deserts. Twin engined aircraft were originally limited to 60 minutes single engine flying time from the nearest diversion airport, meaning transatlantic flights were forced to fly what were known as the 'Blue Spruce Routes' over Iceland, Greenland and into North Eastern Canada. This was waived in the mid-60's by the rise of the three and four engined generation of aircraft such as the Lockheed L-1011 TriStar and the iconic Boeing 747.

The Boeing 767 was a pioneer in ETOPS flying, with TWA being granted 120 minutes single engine flying time.

In 1985 TWA was awarded the first ETOPS certificate to operate its Boeing 767 aircraft up to 120 minutes from a diversion airport, double the original limit. This extra time meant that most transatlantic flights were now possible to complete using more efficient twin engined aircraft.

Since this time engines have become more reliable meaning aircraft manufacturers have been pushing the ETOPS time limit to once unimaginably long flight times. In 1994 the Boeing 777 was the first aircraft to be granted an ETOPS-180 (180 minute) certification from introduction into service. Since then the Airbus A330 has been granted a limit of 240 minutes and the Boeing 777 has the capability to be extended to a massive 330 minutes.

So where does this leave the era of four engined jet transport aircraft? The ever changing aviation industry has shown a constant decrease in sales of four engined aircraft with only the Airbus A380 and Boeing 747-8 still in production. For these mammoths of the sky it seems the only reason to have four engines is due to the power required, but with rocketing fuel costs and the extra maintenance of two added engines, it would appear that the sun is setting on the days of '4 engines 4 long haul' and is shining ever brighter in the world of twin jet transport aircraft.

The final nails in the coffin may well have been dealt this year with the Boeing 787 having certification from the FAA for 330 minutes of single engine flying time from a suitable diversion aerodrome. This puts most corners of the world within reach.

Not to be outdone, Airbus made a major announcement this week confirming a long discussed rumour. The A350XWB is currently flying around the world on a multitude of long range test flights and on arrival at Sydney's Kingsford Smith Airport the news officially broke that Airbus was pursuing an ETOPS rating of a massive 420 minutes, or 7 hours! This rating would make the A350XWB able to reach any airport in the world, leaving only South Polar routes out of it's range.

The ultra modern Airbus A350-900 XWB is pushing for 420 minutes ETOPS rating, putting only south polar routes out of its reach.

Unless passenger capacity is the absolute goal, or an airline chooses to have a flagship aircraft for its most iconic routes, it seems that the financial cost of carrying two more engines far outweighs its realistic practicality in modern day air transport. If the Airbus reaches this remarkable feat, one has to ask, should we now be saying '2 engines 4 long haul'?